Incubating slit sampler



Wing M Nov. 8, 1960 INCUBATING SLIT SAMPLER Filed April 21, 1959 INVENTORS Lee M. Buchanan Herbert H. Decker fiober Porter ATTORNEY H.IM. DECKER ETAL 2,959,523

United States Patent INCUBATIN G SLIT SAMPLER Herbert M. Decker and Lee M. Buchanan, Frederick, and Robert Porter, Bethesda, Md., assigors to the United States of America as represented by the Secretary of the Army Filed Apr. 21, 1959, Ser. No. 807,965

4 Claims. (Cl. 195-139) (Granted under Title 35, US. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment to us of any royalty thereon.

This invention relates to a slit sampler. More specifically, it relates to a sampler having an elongated slit for drawing air into the mechanism. This air is made to impinge on a moving nutrient surface whereby a ribbon of particulate matter is deposited on the medium. Following the deposition, the nutrient medium passes into a heated zone whereby incubation of viable particles in the sample commences immediately. This procedure is in direct contrast to the prior art where incubation was delayed until the entire sampling operation was complete and the medium could be removed from the sampler and placed in an incubator.

In the drawing, represents the sampler box having a tight fitting, removable cover 12. A removable loading closure 14, with handle, appears at the forward end and a corresponding unloading closure 16 appears at the rear end of the sampler. Inside of the sampler box are side rails 18 and a central lead screw 20, the latter being driven by motor and reducing gear 22. Tray 24 is equipped to contain a nutrient medium and is positioned to slide on side rails 18. Half nut 26, which is attached to tray 24, engages load screw 20 which serves to propel it at a uniform rate from the front to the rear of the sampler box. In practice, this may take up to 12 hours, but the speed can be varied by the substitution of different speed reducing gears in the motor housing. Heating element 30 which is controlled by thermostat 32 maintains the rear end of the box at incubation temperature, while dividing walls 34 above and 36 below the moving tray constitute a slotted wall and serve to confine the incubation temperature to the rear of the box. This has the advantage that the nutrient medium does not dry out prior to the deposition. The end of lead screw 20 is journalled in the lower dividing wall 36. Microswitch 38 controls motor 22 and heating element 30 and is positioned such that it will interrupt the circuit to the motor and heating element when the half nut 26 passes beyond the threads on lead screw 20.

Sampling slit 42 is positioned in the bottom of threaded cylinder 40. The latter is screwed into a threaded opening in cover 12 and the sampling slit can be brought into any desired proximity of the nutrient surface in tray 24 by merely screwing cylinder 40 in or out of the cover 12. Sampling slit 42 is also adjustable in width whereby the velocity of the entering air can be varied to produce deposition of even the smallest particle sizes. This adjustable slit coupled with the adjustment in clearance permits a wide variation in operating characteristics. Exhaust nipple 44 completes the structure.

In operation, current is supplied to motor 22 and heating element 30 and an exhaust system is attached to nipple 44. Tray 24 with the nutrient medium is inserted in the forward end of the sampler and half nut 26 is engaged with lead screw 20. Sampling slit 42 is adjusted to the desired size and its spacing is determined. The motor, heater and exhaust systems are then started.

As air is exhausted from the sampler cabinet, air is simultaneously drawn in through slit 42. The particulate matter in this inspired air is deposited in a uniform ribbon as tray 24 moves under the slit. Following the deposition, the tray passes dividing walls 34 and 36 into the heated area of the sampler where incubation of any viable organisms starts and continues while the balance of the sampling is completed. Since this will involve several hours time in any case, it means that incubation of the initial sample is well under way before the sampling run is completed. This in turn results in a great economy of time and makes possible a prompt analysis 7 of the deposited matter.

We claim:

1. In a slit sampler including a sampler body, a sampling slit in said body, a moving nutrient medium beneath said slit and an exhaust system for said sampler body, the improvement which comprises a slotted dividing wall in said sampler body adjacent one side of said sampling slit, means for moving said nutrient medium under said slit and through said slotted dividing wall, a thermostatically controlled heating element on the side of said dividing wall opposite from said sampling slit, which element serves to maintain this section of said sampler body and nutrient medium therein at incubation temperature, immediately after its exposure to the sampling slit.

2. A structure in accordance with claim 1 wherein the sampler is rectangular in shape and wherein the. dividing wall is positioned transversely of said sampler body and said nutrient medium moves longitudinally of 7 said sampler body.

3. A structure in accordance with claim 2 wherein said nutrient medium is contained in a tray supported on rails along the sides of said sampler body and is moved by a lead screw extending longitudinally down the center of said sampler body.

4. A structure in accordance with claim 1 wherein the sampler slit is positioned in one end of a threaded cylinder and wherein said cylinder is screwed into a threaded opening in said sampler body whereby the elevation of the slit above the nutrient medium can be adjusted.

No references cited. 

1. IN A SLIT SAMPLER INCLUDING A SAMPLER BODY, A SAMPLING SLIT IN SAID BODY, A MOVING NUTRIENT MEDIUM BENEATH SAID SLIT AND AN EXHAUST SYSTEM FOR SAID SAMPLER BODY, THE IMPROVEMENT WHICH COMPRISES A SLOTTED DIVIDING WALL IN SAID SAMPLER BODY ADJACENT ONE SIDE OF SAID SAMPLING SLIT, MEANS FOR MOVING SAID NUTRIENT MEDIUM UNDER SAID SLIT AND THROUGH SAID SLOTTED DIVIDING WALL, A THERMOSTATICALLY CONTROLLED HEATING ELEMENT ON THE SIDE OF SAID DIVIDING WALL OPPOSITE FROM SAID SAMPLING SLIT, WHICH ELEMENT SERVES TO MAINTAIN THIS SECTION OF SAID SAMPLER BODY AND NUTRIENT MEDIUM THEREIN AT INCUBATION TEMPERATURE, IMMEDIATELY AFTER ITS EXPOSURE TO THE SAMPLING SLIT. 